1. Field of the Invention
The present invention relates to a head slider of a magnetic recording device.
2. Description of the Related Art
In a magnetic recording device, a head slider equipped with a record transducer (also simply referred to as “head” in the present invention) reads and writes information, while floating over a hard disk or a magnetic recording medium.
The distance between the head and a magnetic layer that records (writes) and/or reproduces (reads) magnetic information on the hard disk, is called a magnetic spacing. The smaller the magnetic spacing is, the more improved the recording density is. Accordingly, the present level of the floating gap for a head has become as small as 10 nm or less as a result of a strong need for higher recording density in recent years. In such an ultra-small floating gap, only a small amount of contaminants adhered onto a head slider may make the floating stability of the head greatly out of balance.
Volatile organic materials, debris. etc. brought about from the environment are examples of such contaminants. As the head slider moves, volatile organic materials, debris. etc. adhered to the hard disk are scraped together and collected on the head slider, and eventually fill in the head floating gap, resulting in head crashing.
Various methods are suggested to solve the problem described above. For example, a method is proposed to restrain adhesion of contaminants by providing a head slider surface that faces a magnetic recording medium (also simply referred to as “head slider surface” in the present specification) with patterning so as to decrease the surface energy (see Japanese Unexamined Patent Application Publication No. H09-219077). However, this method has a disadvantage that a high production cost is inevitable for the manufacturing of head sliders.
Also, a method is suggested in which a self-assembled membrane is formed on the head slider surface to decrease the surface energy (see, for example, Unexamined Patent Application Publication No. H11-16313). However, the film thickness of the self-assembled membrane (or the length of a molecular chain) is rather large, requiring wide magnetic spacing. Accordingly, this is not suitable for a higher recording density. Furthermore, the self-assembled membrane employed in this method comprises silicon that is known as a substance that tends to bring about head crashing. This also makes a drawback against the practical application.
Furthermore, it is proposed to decrease the adhesion of contaminants by applying a lubricant that is the same as or resembles to a lubricant applied to a hard disk, onto the head slider surface and the surface of a head slider protection layer (also referred to as “head protection layer” in the present specification), followed by UV-ray irradiation so as to lower the surface energy (see Japanese Unexamined Patent Application Publication No. H07-85438, for example). However, this method is disadvantageous in the following point. It is known in general that the lubricant is transferred from the disk surface to the head slider surface side by means of evaporation from the disk and intermittent contact with the head slider, etc., with the result that a film as thick as the lubricant layer on the disk is formed on the outermost head slider surface facing the disk (also referred to as “ABS” that is an abbreviation of “air bearing surface”). In a device having a sufficiently wide floating gap, such lubricants adhered to the ABS have been posing little problem. However, as the floating gap has been made smaller, it has come to be generally known that this behavior makes the floating of the head unstable. It is understood that the floating is obstructed by the lubricant on the ABS contacting with the disk, and forming a liquid bridge.
One advantage of this method is that the liquid lubricant layer is made into a solid form by fixing the lubricant applied to the head slider by means of UV ray irradiation, thus leaving the liquid bridging less liable to occur. However, simple application of such a lubricant having a polar molecular end group as disclosed in Japanese Unexamined Patent Application Publication No. H07-85438 will incur coagulation of the lubricant due to its cohesive force, and accordingly, not only solidifying of the lubricant with UV ray irradiation will result in uneven coating but also the height of the coagulated lubricant occupies a substantial portion of the floating gap, sometimes resulting in floating problems such as failure of floating of the head slider, head crashing, scratching of the magnetic recording medium, etc. Also, depending on the level of UV ray irradiation, part of the head slider lubricant layer (also referred to as “head lubricant layer” in the present invention) may exist as a liquid. Such part will still cause liquid bridging, letting down the expected effect.
As described above, it is difficult to achieve both of reduction of adhered contaminants to a head slider and ultra-low floating properties of the head slider. There is also a problem of coagulation of a resin that forms the head lubricant layer. Accordingly, there is a need for solving these problems. It is an object of the present invention to solve these problems, and provide technologies that can achieve reduction of adhered contaminants on a head slider, prevention of coagulation of a resin for forming the head lubricant layer, and ultra-low floating properties of the head slider. Other objects and advantages of the present invention will be clarified through the following explanation.